The creator of a video production typically controls tones and colors so that, when viewed, the video content has a desired appearance as guided by the creator's creative intent. For example, a creator may wish some scenes to have a darker, more oppressive, feel than others. This may include performing color grading (or ‘color timing’) on the source video data.
Various display technologies are now available. For example, there are CRT-based displays, plasma displays, displays backlit by a variety of types of light sources including LEDs of various types, fluorescent lamps, high-intensity incandescent lamps, digital cinema displays etc. A particular display combines display hardware with video signal processing components that receive video signals and drive the display hardware to display video content of the video signals.
Different displays may vary significantly with respect to features such as:                the color gamut that can be reproduced by the display;        the maximum brightness achievable;        contrast ratio;        resolution;        acceptable input signal formats;        color depth;        white level;        black level;        white point;        grey steps;        etc.        
Consequently, the same video content may appear different when played back on different displays. Video content displayed on some displays without modification may depart from the creator's creative intent in one or more ways.
Some current displays can outperform displays that were state-of-the-art at a time when certain video content was created. For example, the displays may be capable of providing images that have brighter highlights, greater contrast, and/or wider color gamuts than legacy displays that were originally available when the video production was created. It would be desirable to take advantage of these improved capabilities without departing significantly from the creative intent embodied in the video content.
It may be desirable to play video content created to take advantage of high performance displays on legacy displays or displays that have lower capabilities. It would be desirable to provide methods and apparatus for adapting the way that the video is played to preserve as much as possible a creative intent embodied in the video content.
Different viewing environments may also cause video content to be perceived differently by viewers. For example, viewers may perceive the same video presentation presented on the same display differently depending on whether the display is being viewed in a dark room or in a brightly lit room. It would be desirable to adapt the playback of video content taking into account the environment in which the video content is being viewed to preserve as much as possible a creative intent embodied in the video content.
There remains a need for apparatus and methods which may be applied to 30 adjust video signals such that the video content has a desired appearance when played.